Effects of close-up dietary energy strategy and prepartal dietary monensin on production and metabolism in Holstein cows
The objective of this study was to evaluate the inclusion of 22 g/ton of monensin (M) in a single group diet (controlled energy-high fiber, CE) and a two-group diet (CE during the far-off and a high energy diet during close-up, CU) during the dry period (DP) on production and metabolism in the first 84 days postpartum. The CE diet was formulated for a dietary energy concentration of 1.30 Mcal NEL /kg DM and the CU diet for 1.49 Mcal NEL /kg DM. A total of 102 cows (70 multiparous and 32 primiparous) were assigned randomly to 1 of the 4 treatments in a 2 (CE or CE/CU DP feeding strategy) × 2 (inclusion of 0 or 22 g/ton of M) factorial arrangement. After calving, all cows received a lactation diet formulated for a dietary energy concentration of 1.70 Mcal NEL /kg DM and 14 g/ton of M. Liver samples were obtained of a subset of mature cows at -10 and 7 d relative to calving. Dry matter intake (DMI) was not affected by the inclusion of M or diet fed during the far-off period, but was 1.7 kg greater during the close-up period for cows that were fed the CU diet than cows fed CE (P < 0.001). None of the treatments affected DMI, body weight, or body condition score during the 84 d of lactation. Neither of the feeding strategies affected milk yield, milk component yields, percentage of milk protein, or fat-corrected milk except that percentage of milk fat was higher for CU than for CE (P = 0.03). The inclusion of M increased lactose content (P < 0.01) and yields of lactose (P = 0.03), fat (P = 0.01), total solids (P = 0.03), and FCM (P = 0.01), and tended to increase milk yield (P = 0.06). Fat, protein, and total solids contents were not affected by the inclusion of M. Cows that were fed CE had greater NEFA concentrations prepartum (P < 0.01) but lower NEFA postpartum (P = 0.05). The inclusion of M during the DP did not affect prepartum or postpartum NEFA and BHBA concentrations. Concentrations of total lipid, triglyceride, and glycogen in liver of mature cows were not affected by treatments. . Feeding a diet of higher dietary energy density for 21 d before calving did not benefit production or metabolism. The CU treatment increased milk fat content, but it was probably due to the higher NEFA concentration. The inclusion of M in the DP increased yields of milk fat, lactose, total solids, and FCM.
monensin, prepartum dietary energy, metabolism
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign